tell application "System Events"
    if UI elements enabled then
        set FrontApplication to (get name of every process whose frontmost is true) as string
        tell process FrontApplication
            click button 2 of window 1
            --button 2 is the green "zoom" button for all applications
            --window 1 is always the frontmost window.
        end tell
    else
        tell application "System Preferences"
            activate
            set current pane to pane "com.apple.preference.universalaccess"
            display dialog "UI element scripting is not enabled. Check 'Enable access for assistive devices'"
        end tell
    end if
end tell
